Crohn-like lymphoid reaction (CLR) in colorectal carcinoma (CRC) is associated with a favourable prognosis and microsatellite instability-high (MSI-H) status. However, there is a lack of consensus on optimal criteria for CLR assessment. The aim of this study was to comparatively validate traditional and novel assessment criteria for CLR.Methods
CLR status in 212 MSI-H CRCs was assessed independently by two pathologists using three different criteria: (1) traditional semiquantitative criteria (Graham-Appelman criteria), (2) the largest lymphoid aggregate (LA) size-based criteria (Ueno criteria) and (3) LA density-based criteria (Väyrynen-Mäkinen criteria).Results
Among the three criteria, the Väyrynen-Mäkinen criteria-based CLR assessment showed the best interobserver agreement (κ value, 0.71; intraclass correlation coefficient, 0.76). Pathologically, intense CLR (grade 2) by Graham-Appelman criteria, active CLR (largest LA size ≥1□mm) by Ueno criteria and high-density CLR (≥0.38□LAs/mm) by Väyrynen-Mäkinen criteria significantly correlated with an early cancer stage (stage I/II). In Kaplan-Meier analysis, both CLR statuses determined by Ueno criteria and Väyrynen-Mäkinen criteria were associated with significant differences in disease-free survival in MSI-H CRC patients (p=0.005 and p=0.001, respectively). In multivariable analysis, both active CLR and high-density CLR proved to be independent favourable prognostic factors in MSI-H CRC (HR, 0.47; 95% CI 0.24 to 0.9 for active CLR and HR, 0.5; 95% CI 0.28 to 0.89 for high-density CLR).Conclusions
Our study confirms that the two recently suggested criteria (Ueno criteria and Väyrynen-Mäkinen criteria) for CLR assessment are fairly reproducible methods and can serve as superior prognosticators in CRC.